Composition and Method for Reducing Friction in Internal Combustion Engines

ABSTRACT

A fuel composition comprising a combustible fuel, an effective friction reducing amount of at least one C 6  to C 30  aliphatic amine, and a detergent package is disclosed, as well as a method of reducing the amount of friction in an internal combustion engine by adding the fuel composition to the engine.

This application claims the benefit of U.S. Provisional Application No.61/288,463 filed Dec. 21, 2009, the entirety of which is expresslyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to friction modifiers and, moreparticularly, to a new fuel composition and method for reducing frictionin internal combustion engines.

BACKGROUND OF THE INVENTION

Much of the focus over the past twenty years has been devoted to fueladditives which control deposit formation in the fuel induction systemsof spark ignition internal combustion engines. These deposit controladditives have been formulated to effectively control carbonaceousdeposits on the fuel injectors, the intake valves and the combustionchamber in an effort to maintain or achieve engine cleanliness.

As crude consumption and fuel costs steadily increased over the pastdecade, consumers have expressed a growing interest and have placed agreater emphasis on the importance of improvements in vehicle fueleconomy. In particular, there has been a strong consumer interest foradditives which can offer reduced engine wear, lower emissions, andimproved fuel economy. Unfortunately, the deposit control additivesprovide very little friction reduction performance at typicalconcentrations used in commercial fuels. Therefore, no additional fueleconomy benefit would be expected over and above that achieved throughdeposit control within the engine.

During this same time period, there have been many advances in enginedesign directed toward better fuel economy and more power generation(specifically more horsepower and acceleration). Conventional port-fuelinjection (PFI) is the primary fuel delivery technology used in gasolineengines. PFI engines inject gasoline into the intake port along with theintake air to form a homogeneous mixture for combustion. This is done inan attempt to optimize the combustion of the fuel and provide improvedengine performance. In addition, many other engine management controltechnologies have been developed to further optimize the combustionprocess for improved fuel economy in PFI engines.

More recently, gasoline direct injection (GDI) engines have beendeveloped to provide improved fuel economy while maintaining orgenerating more engine-out power. The GDI engine injects gasolinedirectly into the combustion chamber separate from the air intake whichallows the engine management system to better optimize the combustionprocess according to the load conditions. Both PFI and GDI enginesrequire fuel additives to control deposits in the injectors, intakevalves and combustion chamber. In addition, further fuel economyimprovement could be achieved by reducing the friction between thecylinder liner and piston ring interface, the valve train and the fuelpump, especially in GDI engines. Therefore, there is a need in thepetroleum industry to develop a fuel and fuel additive package thataddresses the engine deposit and friction reduction requirements of PFIand GDI engines.

Due to the fact that lubricants have traditionally been used to minimizeengine friction, and an estimated 25 to 50% of the frictional losses ofan engine occur at the cylinder liner and piston ring interface, thelubricant industry was the first to focus on reducing engine frictionand improving fuel economy. Improvements in fuel economy have beenachieved through the lowering of the motor oil viscosity. However, atconditions where the engine is working hard (high load and hightemperature), such as hard acceleration or going up hill, lowerviscosity oils can produce very thin lubricant films which may increasethe potential for metal-to-metal contact and lead to wear and higherfriction, i.e., lower fuel economy. To help reduce this contact andimprove engine lubrication under these boundary layer conditions, bothinorganic and organic friction modifiers have been utilized, but GF-4motor oil requirements have reduced the level of inorganic frictionmodifiers allowed due to phosphorus deactivation of the catalyticconverter. This has forced the lubricant industry to rely more heavilyon organic friction modifiers.

Organic friction modifiers are compounds that can affect the boundarylayer conditions experienced by the cylinder liner and piston ringinterface under these severe engine operating conditions. These types offriction modifiers are surface active and produce a protective coatingon the metal surface of the engine by forming a monolayer through theinteraction of the metal surface with the polar end of the frictionmodifier. Subsequent layers of the friction modifier can then build upto provide friction reduction in the boundary layer and help to preventthe two surfaces and their asperities from contacting each other. Thechallenge in overcoming the frictional design limitations, however, liesin identifying a friction modifier which can influence the boundarylayer properties without leading to undesirable effects, such as intakevalve deposits and oil thickening.

The application of organic friction modifiers in combustible fuels hasbeen pursued for some time with minimal success. Friction modifieradditives and detergents commonly added to combustible fuels aregenerally higher molecular weight compounds that may not be completelyburned during the combustion process within spark ignition engines. As aresult, some of the additive interacts with the lubricant oil filmpresent in the combustion cylinder. This interaction allows some of theadditive to become mixed with the lubricant. As the lubricant oil filmis replenished, it becomes mixed with fresh lubricant from the mainlubricant reservoir and some of the absorbed additive migrates past thepiston rings and into the oil pan. As a result, there is a slow transferof additive from the fuel to the lubricant. Depending on the drivingcycle, the amount of additive that is transferred from the fuel to thelubricant can be as high as about 30%. Based on typical frictionmodifier additive concentrations expected for gasoline, this level oftransfer may lead to friction modifier concentrations in the lubricantof up to about 0.5 wt % over a 5,000 mile lube drain interval.Therefore, the addition of an organic friction modifier to a combustiblefuel can impact the cylinder liner and piston ring frictionalinteraction directly within the combustion chamber and can alsoaccumulate in a lubricant to improve the frictional properties in otherparts of the engine drive train contacted by the motor oil (e.g., valvetrain, cam shaft, bearings, etc.). This transfer of the frictionmodifier is known in the art and taught, for example, in WO 01/72390 A2,which describes the delivery mechanism by which a fuel born frictionmodifier can be transferred to the cylinder liner/piston ring interfaceand can accumulate in the lubricating oil sump, thus resulting inimproved lubrication throughout the engine.

Accordingly, it would be desirable to provide a new fuel compositionwhich contains a combustible fuel, a detergent package and a frictionmodifier that has a strong affinity for metal surfaces, but not sostrong as to leave deposits. It would also be desirable to provide amethod for reducing the amount of friction in an internal combustionengine by adding the new fuel composition to the engine to positivelyimpact the friction of the cylinder liner and piston ring interface andthe drive train of the engine, and lead to lower emissions, higher fueleconomy and increased net horsepower.

SUMMARY OF THE INVENTION

In accordance with the present invention, the fuel composition comprisesa combustible fuel, an effective friction reducing amount of at leastone C₆ to C₃₀ aliphatic amine, and a detergent package.

In another aspect, the invention provides a fuel additive compositioncomprising an effective friction reducing amount of at least one C₆ toC₃₀ aliphatic amine and a detergent package.

The invention also provides a method of reducing the amount of frictionin an internal combustion engine comprising the step of adding to theengine a fuel composition comprising a combustible fuel, an effectivefriction reducing amount of at least one C₆ to C₃₀ aliphatic amine, anda detergent package.

The inventive method effectively reduces the amount of friction in aninternal combustion engine by adding the fuel composition of the presentinvention to the engine, thus leading to lower emissions, higher fueleconomy, and increased net horsepower.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a new fuel composition and methodfor reducing the amount of friction in an internal combustion engine. Inaccordance with the invention, the fuel composition comprises acombustible fuel, an effective friction reducing amount of at least oneC₆ to C₃₀ aliphatic amine, and a detergent package. The fuel compositionis added to the internal combustion engine to effectively reduce theamount of friction in the engine.

In accordance with the invention, the combustible fuels which may beused include gasoline and diesel fuel, with the preferred fuel beinggasoline. Gasoline comprises blends of C₄-C₁₂ hydrocarbons which boil inthe range of 25° C. to 225° C., and satisfy international gasolinespecifications, such as ASTM D-4814 and EN228. These gasoline blendstypically contain mixtures of normal and branched paraffins, olefins,aromatics and naphthenic hydrocarbons, and other liquid hydrocarboncontaining components suitable for spark ignition gasoline engines, suchas conventional alcohols and ethers.

The gasoline can be derived from petroleum crude oil by conventionalrefining and blending processes, such as straight run distillation,hydrocracking, fluid catalytic cracking, thermal cracking, and variousreforming technologies.

The C₆ to C₃₀ aliphatic amines which may be used as friction modifiersin the practice of the invention include saturated fatty acid amines,unsaturated fatty acid amines, and mixtures thereof. Preferable C₆ toC₃₀ aliphatic amines include, but are not limited to, octyl-, decyl-,dodecyl-, tetradecyl-, hexadecyl-, hexadecenyl-, octadecyl-,octadecenyl-amines, and mixtures thereof. Tallow amines are particularlypreferred C₆ to C₃₀ aliphatic amines, with hydrogenated tallow aminesbeing most preferred. An example of a suitable hydrogenated tallow amineis Armeen®HTD, available from Akzo Nobel Surface Chemistry LLC.

The fuel composition preferably contains an effective friction reducingamount of the C₆ to C₃₀ aliphatic amine in the range of from about 1 ppmto about 2000 ppm (parts per million). More preferably, the amount ofthe C₆ to C₃₀ aliphatic amine present in the fuel composition is in therange of from about 5 ppm to about 1000 ppm, with about 10 ppm to about500 ppm being most preferred.

The detergent packages which may be used in the practice of the presentinvention are well known to those skilled in the art and commerciallyavailable. Suitable commercial detergent packages include, but are notlimited to, Keropur® and Kerocom® packages available from BASF A.G.,HiTEC® packages available from Afton Chemical Corporation, and OGA®packages available from Chevron Oronite Company LLC.

The detergent packages typically include at least one deposit controladditive, a corrosion inhibitor, a carrier fluid, and a solvent. Somecommercially available detergent packages do not contain a corrosioninhibitor and may be used in the practice of the present invention,however, it is preferred that a corrosion inhibitor be included. Theappropriate amount of each component in the detergent package will varydepending upon the specific engine performance benefit being sought andcan be readily determined by those skilled in the art.

The detergent package typically contains at least one high molecularweight nitrogen-containing deposit control additive. Examples of suchdeposit control additives include polyalkylene amines, polyalkylenesuccinimides, Mannich bases, and polyether amines. The preferred depositcontrol additive for use in the present invention is a polyisobutylene(FIB) amine. Examples of suitable PIB-amines are taught in U.S. Pat. No.4,832,702, the disclosure of which is incorporated herein by reference.

The corrosion inhibitors which may be utilized in the practice of thepresent invention include, but are not limited to, monomers, dimers, andtrimers of long chain organic acids, and various esters, imides,thiadiazoles, and triazoles.

The carrier fluids which may be used in the detergent package arepreferably compatible with the combustible fuel and have the ability todissolve or disperse the components of the detergent package. Examplesof conventional carrier fluids include mineral oils and synthetic oils,such as poly a-olefin oligomers, polyethers, polyether amines, andcarboxylic esters of long chain alkanols.

There are various alcohols and aromatic hydrocarbons which may be usedas solvents in the practice of the present invention. Examples ofsuitable solvents include xylenes, toluene, tetrahydrofuran, isopropanolisobutylcarbinol, and n-butanol; and petroleum hydrocarbon solvents,such as naphtha and the like.

The fuel composition may comprise another friction modifier inaccordance with the present invention. It was discovered that whencertain friction modifier combinations are utilized, greater coefficientof friction reduction is achieved than when either friction modifier isused alone. In particular, when a glycerol monoalkyl ether, morepreferably, a glycerol monooleyl ether is combined with a hydrogenatedtallow amine, the interaction of the two friction modifiers leads tosignificantly improved lubricity.

The fuel composition preferably contains an effective friction reducingamount of the glycerol monoalkyl ether in the range of from about 1 ppmto about 1000 ppm. More preferably, the amount of the glycerol monoalkylether present in the fuel composition is in the range of from about 5ppm to about 500 ppm, with about 10 ppm to about 250 ppm being mostpreferred.

The fuel composition may be added to an internal combustion engine byany conventional method and can be used in internal combustion enginesthat burn liquid fuel, especially spark-ignited gasoline enginesencompassing carbureted, PFI and GDI, as well as in vehicles containingcompression-ignited engines, such as diesel engines. When combustion ofthe fuel composition is achieved in the internal combustion engine, theamount of friction in the engine is effectively reduced, thus leading tolower emissions, higher fuel economy, and increased net horsepower.

In another aspect of the present invention, a fuel additive compositioncontaining an effective friction reducing amount of at least one C₆ toC₃₀ aliphatic amine and a detergent package is provided. All of thesuitable components which may be used in the fuel additive compositionand their respective amounts are the same as those described above withrespect to the fuel composition. The fuel additive may be combined witha combustible fuel in any conventional manner generally known to thosehaving ordinary skill in the art to which this invention pertains andthen added to an internal combustion engine to effectively reduce theamount of friction in the engine.

EXAMPLES

The following examples are intended to be illustrative of the presentinvention and to teach one of ordinary skill how to make and use theinvention. These examples are not intended to limit the invention or itsprotection in any way.

Example 1

An SRV® instrument was utilized to determine the performance of a numberof friction modifier additives. The SRV instrument measures thecoefficient of friction and wear scar of a lubricant resulting from theoscillation of a ball on a disc at a constant set of conditions. SRVreciprocation tests were done using a commercial Castrol GTX® 5W30(GF-4) motor oil that was spiked with various commercially availableorganic friction modifier additives.

The organic friction modifier additives tested were glycerol monooleate(GMO), which was obtained from Oronite Chemical Company, oleylamide(Crodamide® O), obtained from Croda Chemicals, glycerol monooleyl ether(FM-618C), obtained from Adeka USA, and hydrogenated tallow amine(Armeen HTD), obtained from Akzo Nobel Surface Chemistry LLC. Testsamples were prepared by mixing 0.5 grams of the organic frictionmodifier with 99.5 grams of the Castrol GTX 5W30 motor oil.

The SRV instrument uses a steel ball as the upper test piece and a steeldisk as the lower test piece. An oil sample was placed on the disk, aload was applied to the ball from the top, and the ball was vibratedparallel to the disk as the ball was pressed against the disk. Thelateral load applied to the disk was measured to calculate thecoefficient of friction. The coefficient of friction was taken as theaverage of the data for a particular temperature. The SRV testconditions were 50 N load, 50 Hz oscillation, 1 mm stroke and 1 hourduration. The initial temperature was set to 80° C. for the first 30minutes of testing and then rapidly raised to 120° C. for the final 30minutes. This procedure provided some indication of the temperaturedependence of the additive's effect on friction reduction attemperatures expected to be encountered between the cylinder liner andpiston ring. The results of the testing are shown below in Table 1.

TABLE 1 Comparison of SRV Results Treat Coefficient of Coefficient ofFriction Friction Modifier Rate Friction % Reduction Additive (wt %) 80°C. 120° C. 80° C. 120° C. None N/A 0.143 0.145 N/A N/A GMO 0.5 0.1370.137 4.2 5.5 Crodamide O 0.5 0.128 0.126 10.5 13.1 FM-618C 0.5 0.1310.130 8.4 10.3 Armeen HTD 0.5 0.128 0.122 10.5 15.9

The data in Table 1 illustrate the superior performance of the ArmeenHTD (hydrogenated tallow amine) relative to other known frictionmodifier additives. These data show that at 120° C., the coefficient offriction can be lowered by approximately 16% relative to that of acommercial Castrol GTX motor oil meeting the GF-4 specifications throughthe use of the Armeen HTD additive. The coefficient of friction valuesare significantly tower than those of the GMO additive (at bothtemperatures) and show improvement over the high temperature data forthe Crodamide O additive. Both the GMO and Crodamide O additives arewell-known friction modifier chemistries and have been used extensivelyin motor vehicle lubricants.

Although the effect of the Armeen HTD friction modifier was measured inmotor oil, one skilled in the art would understand that the addition ofa friction modifier to a combustible fuel results in the accumulation ofthe friction modifier in the motor oil over the typical drain intervalof the vehicle. Therefore, testing of the friction modifier in the motoroil is a reliable alternative to more expensive and complex enginetests.

Therefore, the inventive composition and method can effectively reducethe amount of friction within an internal combustion engine (inparticular, the cylinder liner and piston ring interface and the drivetrain) by producing improved lubricity. The lower friction in turn canlead to lower emissions, higher fuel economy, and an increase in nethorsepower.

Example 2

Intake valve deposit measurements were carried out on a Ford 2.3 Lengine dynamometer Intake Valve Deposit (IVD) clean-up test standaccording to a modified version of the standard ASTM D6201 procedure.Clean valves were installed in the engine and then a retail gasolinewhich contained the minimum amount of detergent additive as required bythe US EPA (i.e., the lowest additive concentration or LAC) was run for50 hours following a Coordinating Research Council (CRC) drive cycle.The engine was disassembled, the valve weights were measured, and thenreassembled to determine the clean-up performance of the test fuelsusing a 100 hour test following the CRC drive cycle. The IVD clean-upperformance results of a comparative detergent package (345 ppmv)containing a PIB-amine, corrosion inhibitor, carrier fluid, solvent anddye, and the detergent package in combination with the Armeen HTDadditive are shown below in Table 2.

TABLE 2 Comparison of IVD Clean-Up Results IVD Friction Modifier TreatRate Average IVD Average IVD Clean-Up, Additive (ppmv) Dirty-Up, mgClean-Up, mg % None N/A 155 93 40 Armeen HTD 125 204 84 59

The results illustrated in Table 2 demonstrate the significantly betterIVD control and detergent clean-up afforded by the combination of thedetergent package and the Armeen HTD friction modifier, as compared tothe detergent package alone. Thus, the Armeen HTD additive is adesirable friction modifier since it has a strong affinity for metalsurfaces, but does not leave deposits.

Example 3

The same SRV testing of the friction modifier additized Castrol GTX 5W30motor oil performed above in Example 1 was conducted in this example todetermine the performance of a combination of additives, namely FM-618Cand Armeen HTD. Additional test samples were prepared by mixing 0.2grams of the organic friction modifier with 99.8 grams of the CastrolGTX 5W30 motor oil. All of the coefficient of friction results fromExample 1 and from the testing in this example of the combination of theFM-618C and Armeen HTD friction modifier additives are shown below inTable 3.

TABLE 3 Comparison of SRV Results Friction Modifier Coefficient ofFriction Additive Treat Rate (wt %) 80° C. 120° C. None N/A 0.143 0.145GMO 0.5 0.137 0.137 Crodamide O 0.5 0.128 0.126 FM-618C 0.2 0.145 0.145FM-618C 0.5 0.131 0.130 Armeen HTD 0.2 0.132 0.129 Armeen HTD 0.5 0.1280.122 FM-618C 0.2 0.126 0.118 Armeen HTD 0.5

The data in Table 3 demonstrate that the combination of a glycerolmonooleyl ether (FM-618C) and a hydrogenated tallow amine (Armeen HTD)provides greater coefficient of friction reductions than either additivealone. The data also show that the FM-618C and Armeen HTD additivecombination provides the lowest coefficient of friction values at bothtemperatures tested, and that the values are lower than those of eitherGMO or Crodamide O, both of which are well-known friction modifierchemistries. In addition, this improvement is contrary to the simpleadditive effect since the coefficient of friction values for the FM-618Cadditive are higher than those of the Armeen HTD additive, and thecombination of the two friction modifier additives resulted in a lowerset of coefficient of friction values.

Therefore, the inventive composition and method improves lubricity andhelps reduce the amount of friction within an internal combustion enginethrough the synergistic interactions of two different friction modifierchemistries added via the fuel. This synergistic behavior effectivelylowers the amount of friction within the cylinder liner and piston ringinterface and the drive train of the internal combustion engine. Thelower friction in turn can lead to lower emissions, higher fuel economy,and an increase in net horsepower.

While the present invention is described above in connection withpreferred or illustrative embodiments, these embodiments are notintended to be exhaustive or limiting of the invention. Rather, theinvention is intended to cover all alternatives, modifications andequivalents included within its spirit and scope, as defined by theappended claims.

1. A fuel composition comprising: a. a combustible fuel; b. an effectivefriction reducing amount of at least one C₆ to C₃₀ aliphatic amine; andc. a detergent package.
 2. The composition of claim 1 wherein thecombustible fuel is selected from the group consisting of gasoline anddiesel fuel.
 3. The composition of claim 1 wherein the C₆ to C₃₀aliphatic amine is selected from the group consisting of saturated fattyacid amines, unsaturated fatty acid amines, and mixtures thereof.
 4. Thecomposition of claim 3 wherein the C₆ to C₃₀ aliphatic amine is selectedfrom the group consisting of octyl-, decyl-, dodecyl-, tetradecyl-,hexadecyl-, hexadecenyl-, octadecyl-, octadecenyl-amines, and mixturesthereof.
 5. The composition of claim 4 wherein the C₆ to C₃₀ aliphaticamine is a tallow amine.
 6. The composition of claim 5 wherein the C₆ toC₃₀ aliphatic amine is a hydrogenated tallow amine.
 7. The compositionof claim 1 wherein the amount of the C₆ to C₃₀ aliphatic amine is in therange of from about 1 ppm to about 2000 ppm.
 8. The composition of claim1 wherein the amount of the C₆ to C₃₀ aliphatic amine is in the range offrom about 5 ppm to about 1000 ppm.
 9. The composition of claim 1wherein the amount of the C₆ to C₃₀ aliphatic amine is in the range offrom about 10 ppm to about 500 ppm.
 10. The composition of claim 1wherein the detergent package comprises: a. at least one deposit controladditive; b. a corrosion inhibitor; c. a carrier fluid; and d. a solvent11. The composition of claim 1 further comprising an effective frictionreducing amount of at least one glycerol monoalkyl ether.
 12. Thecomposition of claim 11 wherein the glycerol monoalkyl ether is aglycerol monooleyl ether.
 13. The composition of claim 11 wherein theamount of the glycerol monoalkyl ether is in the range of from about 1ppm to about 1000 ppm.
 14. The composition of claim 11 wherein theamount of the glycerol monoalkyl ether is in the range of from about 5ppm to about 500 ppm.
 15. The composition of claim 11 wherein the amountof the glycerol monoalkyl ether is in the range of from about 10 ppm toabout 250 ppm.
 16. A fuel additive composition comprising: a. aneffective friction reducing amount of at least one C₆ to C₃₀ aliphaticamine, and b. a detergent package.
 17. The composition of claim 16wherein the C₆ to C₃₀ aliphatic amine is a hydrogenated tallow amine.18. The composition of claim 16 wherein the amount of the C₆ to C₃₀aliphatic amine is in the range of from about 1 ppm to about 2000 ppm.19. The composition of claim 16 wherein the detergent package comprises:a. at least one deposit control additive; b. a corrosion inhibitor; c. acarrier fluid; and d. a solvent.
 20. The composition of claim 16 furthercomprising an effective friction reducing amount of at least oneglycerol monooleyl ether.
 21. The composition of claim 20 wherein theamount of the glycerol monooleyl ether is in the range of from about 1ppm to about 1000 ppm.
 22. A method of reducing the amount of frictionin an internal combustion engine comprising the step of adding to theengine a fuel composition comprising a combustible fuel, an effectivefriction reducing amount of at least one C₆ to C₃₀ aliphatic amine, anda detergent package.
 23. The method of claim 22 wherein the C₆ to C₃₀aliphatic amine is a hydrogenated tallow amine.
 24. The method of claim22 wherein the amount of the C₆ to C₃₀ aliphatic amine is in the rangeof from about 1 ppm to about 2000 ppm.
 25. The method of claim 22wherein the detergent package comprises: a. at least one deposit controladditive; b. a corrosion inhibitor; c. a carrier fluid; and d. asolvent.
 26. The method of claim 22 further comprising an effectivefriction reducing amount of at least one glycerol monooleyl ether. 27.The method of claim 26 wherein the amount of the glycerol monooleylether is in the range of from about 1 ppm to about 1000 ppm.